Treatment of hydrocarbons



Patented Aug. 31, 1948 TREATMENT OF HYDROCARBONS Charles L. Thomas, -Winnetka, and Vladimir Haensel, ClarendonHills, Ill., assignors to Uni-. I versal Oil Products-;Company,'Chicago,111., a. corporation of Delaware H No Drawing. Originalapplication February 20,

1939, Serial No. 257,464. .'Divided and this application'June 8,1946, Serial N0.'.675,328 I 5 Claims, (01. 269 -671).

This application is a division of our copending application Serial No. 257,464 filed February 20, 1939, now Patent No. 2,410,111, October 29, 1946.

This invention relates particularly to the manufacture of alkylated aromatichydrocarbons, and in a more specific sense has reference to a process of contacting aromatic hydrocarbons with olefinic hydrocarbons or substances capable of producing olefinic hydrocarbons in situ with catalysts whereby to produce alkylated aromatic hydrocarbons which may be used as such, as components of motor fuel, or as intermediates in organic syntheses.

It,is a noteworthy fact in any particular organic reaction involving the decomposition of single compounds, or the interaction of two or more compounds, that many times the reaction velocity constants are of a low order under moderate conditions of temperature and pressure corresponding to a low order of secondary'or side reactions, these latter resulting in the alteration of the primary desired products. For different reactions catalysts of extremely variable character have been found empirically which accelerate the reaction sufllciently'so that a laboratory process can be operated upon a commercial scale.

Very few rules have been evolved which enable the prediction of the catalytic activity of any substance in a given organic reaction or the selection of a particular substance for a particular reaction. Metals, metal oxides, metal salts, and various acids and alkalies, and substances of an ordinarily inert character, which furnish an absorbent contacting surface, have been tried and in difierent instances have proved effective. The type of catalysts which characterizes the process of the present invention is of an absorptive character and comprises preferably synthetically prepared masses of silica and oxides selected from the group comprising alumina, zirconia, and

thoria.

In one specific embodiment the present invention comprises subjecting aromatic hydrocarbons and olefins or substances capable of producing olefins in situ, to contact with catalysts comprising synthetically prepared composite masses of silica and one or more of alumina, zirconia, and thoria at an elevated temperature, whereby to produce substantial yields of alkylated aromatic hydrocarbons.

According to the process of the present invention mixtures of aromatic and olefinic hydrocarbons ar contacted with the above mentioned silica-base catalysts at temperatures in the approximate range of 359-850" F. preferably under I pressures in the range of 500-2000 pounds per square inch, under which conditions substantial proportions of the reactants areconverted into alkylated aromatic hydrocarbons, the monoalkylated derivatives generally being in preponderance. I v,

The preferredSilica-base alkylation catalysts may be I prepared by a number 'of' alternative methods which have certain necessary features in common, as will subsequently be described.

Generally speaking, however, the catalysts may be considered to comprise intimate molecular combinations of silica with alumina, zirconia, and/0r thoria, all of which components possess more or less low; activity individually but display high activity in the aggregate. f Their activity is not an additive function, it being relatively constantfor a wide rangeof proportions of the components whether in. molecular, proportions or fractions of molecular'proportions. No one component may be determined as the one component for which the remaining components maybe considered as the, promoters'according to conventional terminology'nor can any component be definitely stated to be the support and the others as the catalyst proper. I y

According to one general method of preparation the preferred silica-base alkylation catalysts may be prepared by precipitating silicafrom solution'vas a'hydrogel and subsequently admixing or depositing the hydrogels of alumina, zirconia,

and/or thoria uponjthe hydrated'silica. One of 1 v v the more convenient methods of preparing the silica hydrogel is to acidify an aqueous solution of sodiumsilicate by the addition of an acid, such as hydrochloric acid, for example. The excess acid and the concentration of the solution in which the precipitation is brought about determine in some measure the suitability of the silica hydrogel for subsequent deposition of the hydrogels of alumina, zirconia, and/or thoria. In generaLsuitable hydrated silica may be produced by the use of dilute solutions of sodium silicate and the. addition of a moderate excess of acid whereby the desired activesilica gel is obtained and conditions of filtering and washing are atan optimum.

After precipitating the silica hydrogel, it is treated and washed to substantially remove alkali metal ions; It is not known whether the alkali metal ions, such as sodium ions, are present in the primary'gel in chemical combination, or in an adsorbed statebut, it hasbeenj determined deflnitely thattheir removal is necessary if catalysts are to'be obtained suitable for prolonged use in accelerating hydrocarbon conversion reactions of the present character. It is possible that the presence of the alkali metal impurities causes a sintering or fluxing of the surfaces of thecatalyst at elevated temperatures so that the porosity is much reduced with corresponding reduction in effective surface. moved by treating with solutions of acidic materials, ammonium salts, or salts QfaIuminmn, zirconium, and/or thorium. When treating with acids, as for example with hydrochloric acid, the acid extracts the alkali metalimpl rities ima silica gel. The salts formed and acid are then substantially completely removed by water washing treatment. Where ammonium sa1ts, ,or salts of aluminum, zirconium, and/or thorium-are used, the ammonium or multivalent metals (used apparently displace the alkali metal impurities present in the composite and the alkali metal salts formed, together .with the major portion of the multivalent salts, are removedin the water washing treatment. ,Some of the multiv ale'nt metals introduced into the silica, hydrogel inthe purifying treatment. may become 'a permanent part of the composite, whereas in the treatment with ammonium salts small amounts of the ammonium salts remaining after the wasl iin g process, will. be drivenoff in subsequent treatment at elevated-temp r t r In one of. the preferredmethods of compositing the hydrogel materials, the purified precipitated hydrated silica gel may be suspended in asolution of aluminum, zirconium,.,.and/o r thorium salts in the desired proportion and the alumina, zirconia, and/or thoria hydrogel depositedupon the. suspended silica.hydrogel by the additionjof volatile basic precipitants, such as ammonium hydroxide, ammonium, carbonate, ammonium hydrosulfide, ammoniumsulfide, or other materials such as,organic bases may be employed. According tov this method, the purif ed silica .gel maybe suspended in a solution of aluminum chloride, zirconylnitrate, and/or thoriumnitrate, for example, and thev ,hydrated alumina, zirconia, and/or thoria precipitated by the addition of ammonium. hydroxide. In this example, the alumina, zirconia, and/or thoria are co-precipitated.

Alkali metal ions may be re:

. .Alternatively the iidrifieesiii a gel ma j e mixed while inthe wet condition withseparately prepared hydrated alumina, hydrated ,zirconia and/or'hydrated thoria precipitated eithers'eparately,.or. concurrently, asfor ,exampl'e by the addition of volatile basic precipitants to solutions of a1uminum,. zirconium, and/or thorium salts. The. hydrated alumina, hydrated zirconia, and/ or hydrated thoria thus prepared are substantially free; from alkali metalions and can .be mixed with purified silica gel. Howevenif alkalimetal ions are incorporatedjas when the hydrated alumina is prepared from sodium .aluminate, for example, or if zirconium and/or. thorium tetrahydroxides areprecipitated by thefinteractionpf zirconyl nitrate and/or. thorium nitrate and sodium hydroxide, I regulated. purification v tr'ea tment, and water washing, by methods selected from,those described in connection with the purification of hydrated-silica gelto remove alkali .metal ions will-berequired... Care should be observed in the selection andconcentration of reagents used so as. not to. dissolve. unduly; large amounts of alumina, .zirconia and/or thoria.

Asfurther. alternatives .in .the. preparation of silica-base alkylation catalysts, purified silica gel may be added to a solution of salts of aluminum,

zirconia', and/or thorium salts.

, Inthe methods above described, a silica hydrogel freeirom alkali metal ions was admixed or hadld eposite'c l thereon relatively pure hydrated alumina, hydrated zirconia, and/or hydrated thoria prior to the drying treatment. In methods described below,.the hydrated silica with a hydrated alumina, hydrated zirconia, and/or hydrated thoria are concurrently precipitated or admixed and treated to remove the alkali metal ions from the composited materialprior to drying treatment, either in thepresence of the original reactants or subsequent to water washing. Thus, solutions of silicon compounds, more usually alkali metal silicates and soluble aluminum, zirconium, and/or thorium salts may be mixed under regulated conditions of acidity or basicity to jointly precipitate hydrated silica, hydrated alumina, hydrated zirconia, and/or hydrated thoria in varying proportions. For example, solutions of sodium silicate, aluminum chloride, zirconyl nitrate, and/ or thorium nitrate may be mixed and an alkaline or acid reagent added according to the proportions used so that in the mix apH in the range of 3-l0 is obtained. In cases where a sol is formed, the precipitation may be brought about if the sol is acid by the addition of a volatile base, as for example, ammonium hydroxide, and alkali metal salts removed by Water washing, or the composite may be treated as indicated above in connection with the purification of the hydrated silicia to remove alkali metal ions. Various methods are possible for the preparation of the hydrated silica, hydrated alumina, hydrated zirconia, and/or hydrated thoria separately or in combination and the puritying treatment isalwaysnecessary where alkali metal ions are present in substantialamounts.

The character andefiiciency of the ultimately preparedsilicia catalyst supports will vary more or less with precipitation and/or mixing, purification treatment, ratioof components, calcining, etc. av specific example being given below. The ratio of the components may be varied within wide limits-the limiting factor being more in evidence with respect to small proportions than with large proportions of .the various components, In general, it appears that 2-6 mole percent of alumina, zirconia, and/or thoria together. withreference to silica may be considered an approximation of the minimum porportions. ,After the alumina, zirconia, and/or thoria have been mixed with or deposited on the purified silica gel and Water Washed, ii desired,'as described forone general methodof preparation, or after the hydrated silica, hydrated alumina, hydratedzirconia, and/ or hydrated thoria havebeen composited and. treated to remove the alkali metal ions, as described for another general method of preparation, the catalytic materials may berecovered as a filter cake and dried at a temperature in the order of 240-300 F., moreor less, after which they may be formed into particles of a suitableaverage definite size rang ingfrom powder to various forms and sizes obtained by pressing and screening, or otherwise formed into desirable shapes by compression or extrusion methods.

By calcining at temperature of the order of approximately 850-1000 F., or higher, the maximum activity of the silica-base alkylationcatalyst is obtained and a further dehydration occurs so that, for example, after a considerable period of heating at 900 F., the water content,

as determined by analysis, is of the order of Silica-base alkylating catalysts prepared bythe various types of procedures outlined above evi-' dently possess large total contact surfaces corresponding to a desirable porosity, the pores of the catalyst particles being of such size and shape that they do not become clogged with carbonaceous deposit after a lon period of service and are, therefore, not difficult to reactivate by oxidation. This structure is retained, also, after many alternate periods of use and reactivation, as evidenced by the fact that the catalysts may be reactivated rapidly by passing air or other oxidizing gas over the used particles to burn off the decontrollable action with substantially no tendency to oxidize or unduly promote polymerization reactions at the expense of the desired, al-.

kylation. This is particularly in evidence in the case of the iso-olefins. When using sulfuric acid and alkylating with gaseous olefin mixtures, such as those produced as by-products in oil cracking reactions, the polymerization reactions may proceed to the extent of forming polymers of too high molecular weight and boiling point for use in commercial motor fuels and may even produce gummy and resinous polymers which are insoluble and entirely objectionable for this reason. It is not to be inferred, however, that polymerization can be obviated entirely when using synthetic silica-base catalysts.

The reactions between aromatic hydrocarbons and olefinic hydrocarbons in the presence of synthetic silica-base catalysts are fundamentally of a simpler character. The following equation may represent the course of a typical reaction between a mono-olefin and an aromatic hydrocarbon in the presence of catalysts of the present character:

CsHo +CH2CH-CH3- CGH5CH (CH3) 2 Benzene Propene Cumene This equation shows that the union of one molecule each *of benzene and propene produces cumene, otherwise known as isopropylbenzene. The reaction may proceed further tothe production of di-alkylated and poly-alkylated derivatives depending upon conditions of operation, the relative proportions of olefin and aromatic hydrocarbons, and the usual controlling factors such as temperature, pressure, activity of catalysts, and time of contact.

The process of this invention may also be carried out by mixing the olefinic hydrocarbon (or substance such as alcohol, ether, or ester, capable of forming such olefin in situ) with a molar excess, usually approximately 2-4 times its molar equivalent, of aromatic hydrocarbon and then passing the resulting solution through a suitable'tower o-rchamber containing the granular synthetic silica-base catalyst maintained at a temperature in the approximate range of 350- 8509 F. Also-the aromatichydrocarbon and other reactant may be introduced simultaneously into the catalyst chamber from separate sources.

The catalyst may also be inthe form of a fine powder :that moveswith the reacting materials through a heated chamber or reaction zone under elevated pressures preferably in the. range of 500-2000 pounds per squareinch. While it is at times desirable to operate the process of this invention at various temperatures and pressures throughout-the range indicated above, it is not implied that these diilerent conditions of operation are equal or equivalent, nor that their use necessarily leads to the production of alkylation products inthe saine proportions or of the same character; '-It is usual that a particular choice of conditions favors the production of a major proportion of some one or another desired reaction product.

The'following examples are given to illustrate the character .of the results obtained by the use of the process of-the present invention, although the-data presented are only from selected cases and are not introduced withthe intent of restricting unduly the scope of the invention.

' Example 1 An alkylation catalyst prepared according to the process of the present invention comprised approximately 92% silica and 8% alumina on a dry basis, The general procedure observed in preparing this catalyst was to precipitate a silica gel and to free it from alkali metal ions by washing with aluminum chloride solution and to mix the purified silica with alumina precipitated from an aluminum chloride solution by theme of ammonium hydroxide. 550 parts by weight of waterglass was dissolved in 4000 volumes of water and approximately '75 volumes of 2.5 molar hydrochloric acid was added gradually while'agitating. The precipitation was thus carried out in an alkaline medium until finally when all the acid had been added the liquor became acidic to litmus. The precipitated hydrogel was then filtered and Washed twice using approximately 3000 volumes of water per batch. Subsequent washing was with 1500 volumes of water containing 27 parts by weight of aluminum chloride hexahydrate. Then 29 parts by weight of aluminum chloride hexahydrate were dissolved in 1500 volumes of water. The silica prepared and purified, as indicated above, was suspended in this aluminum chloride solution and 6.6 volumes of ammonium hydroxide was added slowly while agitating until the reaction mixture was alkaline to litmus. The precipitated mass was then filtered and washed four times with 2000-3500 volumes of water. The filter cake was dried and a portion of it prepared into 6-10 mesh granules for a test and finally calcined at approximately 932 F,

A mixture of propene and benzene in the molar proportions of 32.8% propene and 67.2% benzene was passed under a pressure of 1900 pounds per square inch through a chamber containing 84.5 parts by weight of the synthetically prepared silica-alumina. alkylation catalyst at a temperature of 530 F. During a period of four hours, 205 parts by weight of the Propane-benzene mixture was charged without the formation of gas or the escape of unchanged propene. Investigation of the liquid products showed that 1.3 molar proportions of propene reacted per molar proportion of benzene. About 22.6% of the benzene-free product consisted of cumene, or isopropyl-benzene. 24% of the theoretical based upon the benzene reacting, or 19 based upon the propene which reacted. A similar experiment made on some of the same propene-benzene mixture in the same apparatus filled with quartz chips gave no alkylation and 99.5% of the benzene passed therethrough was recovered unchanged.

Example 2 the liquid products showed that 1.08 molar equivalents of propene reacted for each molar equivalent of benzene reacting. The cumene fraction was 58.4% of the benzene-free product. This yield corresponded to 68% of the theoretical based upon the benzene which reacted and 56% based on the propene. The cumene fraction was identified by preparation of the diacetamino derivative, which melted at 420 F, (216 (3.), the same as that value given in the literature for this derivative of cumene.

It was noticed that the alkylation reaction was more selective in the production of mono-a1- kylated aromatic hydrocarbon at the higher temperature used in Example 2 than was the case in Example 1.

The nature of the present invention and of its commercial utility can be seen from the specifi- Thi yield corresponded to approximately cation and examples given, though neither section is intended to be unduly limiting on its generally broad scope.

We claim as our invention:

1. A process for producing alkylated aromatics which comprises reacting an aromatic with an olefin in the presence of an alkylating catalyst comprising silica, alumina and thoria.

2. The process as defined in claim 1 further characterized in that said catalyst comprises a calcined mixture of the hydrogels of silica, alumina and thoria.

3. A process for producing alkylated aromatics which comprises reacting an aromatic with an olefin in the presence of an alkylating catalyst comprising silica,'alumina and thoria at a temperature in the approximate range of 350-850 F.

4. An alkylation process which comprises reacting an aromatic hydrocarbon with an olefin in the presence of a catalyst comprising silica gel, alumina and thoria.

5. An alkylation process which comprises reacting an aromatic hydrocarbon with an olefin at a temperature in the approximate range of 350 850 F. and in the presence of a catalyst comprising silica gel, alumina and thoria.

CHARLES L. THOMAS. VLADIMIR HAENSEL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,755,496 Behrman Apr. 22, 1930 2,115,884 Schollkopf May 3, 1938 2,215,305 Voorhees Sept. 1'7, 1940 2,216,262 Bloch Oct. 1, 1940 2,242,960 Sachanen May 20, 1941 2,268,109 Connolly Dec. 30, 1941 

